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Dr. Julianna Tomlinson

Uncovering answers to Parkinson’s disease through innovative research

“When you have a community that says,’ I believe in what you’re doing. I believe in it enough that I’m going to invest in it.’ It validates what we do. What we’re doing is trying to advance the field of research to develop new therapies for Parkinson’s. When you have people believing in us and supporting that work, it’s huge. It makes a difference in our ability to carry out the project.”—Julianna Tomlinson, Senior Research Associate, The Ottawa Hospital

Ten years ago, Dr. Julianna Tomlinson accepted a research position in Dr. Michael Schlossmacher’s lab at The Ottawa Hospital, investigating Parkinson’s disease at the cellular level. But within the first month, she met Shelby Hayter who had been diagnosed with early onset Parkinson’s, and her work took on new meaning.

“The science side was exciting, learning more about the brain and certain diseases. But seeing how this disease affected people and their families brought a new aspect to doing basic research. The goal is to make a difference in peoples’ lives,” said Dr. Tomlinson.

The senior research associate studies the GBA1 gene. A few years ago, it was discovered that people who carry a mutation in this gene are at greater risk of developing Parkinson’s disease. However, the risk is small, as by the age of 80 less than 10 percent of people with a GBA1 mutation will develop Parkinson’s. Nevertheless, mutations in GBA1 represent the commonest genetic risk factor for the illness around the world.

There is a lot known about the GBA1 gene because mutations in both copies of this gene cause the rare illness called Gaucher disease. One form of this disease affects the whole body, which is treatable.

“What is exciting is that we can take what we already know about GBA1 and Gaucher disease, and see if the drugs that are used to treat the disease have potential for treating Parkinson’s,” said Dr. Tomlinson. “It’s promising and brings us steps closer to a treatment.”

In order to help understand how Parkinson’s works and how certain drugs will affect it, Dr. Tomlinson and her research team developed a mouse with the genetic elements of Parkinson’s disease.

The mouse has the GBA1 mutation, as well as more alpha-synuclein than normal. Alpha-synuclein is the protein that accumulates and deposits in the brain of people with Parkinson’s disease. Although, alpha-synuclein is known as the central player in the disease, what it does, how it causes the disease, and how it interacts with GBA1 are still a mystery that researchers at The Ottawa Hospital are hoping to solve.

“The reason this mouse is valuable is because we can use it to test the therapies that target alpha-synuclein and the GBA1 mutation. Both of these are promising drug targets in humans,” said Dr. Tomlinson. “Drug companies that have GBA1 therapies for rare diseases like Gaucher’s are considering whether these drugs could offer therapeutic approaches for a much bigger field – Parkinson’s. Our mouse allows us to test these avenues.”

In a recent genetic study performed at The Ottawa Hospital and CHEO, researchers found that over 16 percent of the individuals with Parkinson’s disease that participated in the study, carry a mutation in their GBA1 gene. Building on this finding is a project directly supported by Partners Investing in Parkinson Research (PIPR). The project will compare the analysis of specific factors in the blood from Parkinson’s patients that carry a mutation in their GBA1 gene, to those that do not. These findings will also be compared to what occurs in the disease mouse model. The goal is to determine if there are markers in the blood that can one day help clinicians to identify patients and/or monitor the disease progression. The study will also look at whether these changes can teach us anything about how mutations in GBA1 contribute to the development of Parkinson’s.

“What we propose to do for the PIPR supported project is to see if there is a link between what we find in the patient samples compared to the mouse,” said Dr. Tomlinson. “We have this unique opportunity with these samples to compare human disease to the diseased mouse. This will allow us to validate how closely our mouse model reflects Parkinson’s in humans, and this will be of great benefit to test drugs.”

Thanks to PIPR and donor support, Dr. Tomlinson’s research is bringing understanding of Parkinson’s disease closer to finding better treatments.